class EmailSender(object):
    def __init__(self, user, password, server_host, port=25, sender_name=None):
        self.password = password
        self.user = user
        self.server_host = server_host
        self.port = port
        self.sender_name = sender_name

        self.subject = "default subject"
        self.recipient_list = []
        self.recipient_address_list = []
        self.msg_content = 'from email sender'
        self.msg = MIMEMultipart()

        self.attached = 0

    def add_recipient(self, address, name):
        formatted = formataddr((Header(name, 'utf-8').encode(), address))
        self.recipient_list.append(formatted)
        self.recipient_address_list.append(address)
        return self

    def set_content(self, message):
        self.msg_content = message
        return self

    def add_attachment(self, file_path, main_type, sub_type, file_name=None):
        if not file_name:
            file_name = file_path.split('/')[-1]
        with open(file_path, 'rb') as f:
            mime = MIMEBase(_maintype=main_type, _subtype=sub_type, filename=file_name)
            mime.add_header('Content-Disposition', 'attachment', filename=file_name)
            mime.add_header('Content-ID', '<{}>'.format(self.attached))
            mime.add_header('X-Attachment-Id', str(self.attached))
            mime.set_payload(f.read())
            encoders.encode_base64(mime)
            self.msg.attach(mime)
        return self

    def set_subject(self, subject):
        self.subject = Header(subject, 'utf-8').encode()
        return self

    def send(self):
        if not self.sender_name:
            name, addr = parseaddr(self.user)
            from_ = Header(name, 'utf-8').encode()
        else:
            from_ = Header(self.sender_name, 'utf-8').encode()
        to_ = ','.join(self.recipient_list)

        mime_text = MIMEText(self.msg_content, 'plain', 'utf-8')
        self.msg.attach(mime_text)
        self.msg['From'] = from_
        self.msg['To'] = to_
        self.msg['Subject'] = self.subject

        server = smtplib.SMTP(self.server_host, self.port)
        server.starttls()
        server.login(self.user, self.password)
        server.sendmail(from_addr=self.user, to_addrs=self.recipient_address_list, msg=self.msg.as_string())
        server.quit()